Lighting installation



Nov. 18, 1958 F. KNOBEL 2,851,219

LIGHTING INSTALLATION Filed Jan. 4, 1955 5 Sheets-Sheet 1 Fig.7

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LIGHTING INSTALLATION Filed Jan. 4, 1955 5 Sheets-Sheet 5 Fig. 10

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IN VEN TOR United States The present invention relates to a lighting installation and more particularly to a lighting installation of the socalled starterless type comprising one or more fluorescent gas discharge lamps of the hot-cathode type, one or more choke coils connected in series with said lamp or lamps, in their supply circuit, and one or more choke coils connected in parallel with said lamp or lamps in an oscillator circuit for igniting them so that a separate starter device is not required. Installations of this kind are likely to difier widely between them according to the number and model of fluorescent lamps provided and according to the available supply voltage, and it has hitherto been usual to provide different choke coils both in the supply and in the oscillator circuits of .the same installation, and in the corresponding circuits of various installations. It was therefore necessary to manufacture and keep in store a large variety of difierent choke coils to suit the various installations, a fact which was reflected in comparatively high costs for their establishment.

It is therefore an object of the present invention to provide the possibility of using the choke coils of one standard model both in the supply circuit and in the oscillator circuit of any one installation and in corresponding circuits of installations widely difteringfrom each other as to the number and model of fluorescent lamps provided and as to the supply voltage. Such standard choke coils may be manufactured in very large numbers and their turnover where kept in store will be greatly increased above that ofany of the numerous models of choke coils hitherto used for such purposes. Accordingly, the cost of the choke coils and that of any installation comprising them will be diminished and the establishment of such installations will be simplified 'to a considerable extent. i

Another object of the present invention is to provide lighting installations of the said kind in which standardized choke-coil units of the same construction and size comprising two choke coils can be used with advantage.

Still another object of the invention is to provide a lighting installation of the said kind in which standardized choke coil and capacitor of the same construction and size, comprising two choke coils and a capacitor, can be used with advantage.

Further objects and advantages of the invention will become apparent from the description, now to follow, of a number of embodiments thereof, which are diagrammatically represented in the accompanying drawings in which:

Fig. 1 is a connecting-diagram for a lighting installation of the said kind comprising one 20-watt fluorescent discharge lamp supplied from a 220-volt network;

Fig. 2 is a connecting diagram for a similar installation comprising three 20-watt lamps;

Fig. 3 similarly represents an installation comprising four 20-watt lamps;

Fig. 4 represents an installation comprising two 40- Watt lamps;

atent O ICC Fig. 5 represents an installation comprising one 40- watt lamp supplied from a l25-volt network;

Fig. 6 represents an alternative installation comprising one 40-watt lamp;

Fig. 7 represents an installation comprising two 65- watt lamps, supplied from a 220-volt network;

Fig. 8 represents an installation comprising one watt lamp, supplied from a l25-volt network;

Fig. 9 represents an installation comprising two 100- watt lamps supplied from a 220-volt network;

Fig. 10 represents an installation comprising one 40- watt lamp supplied from a 220-volt network;

Fig. 11 represents an alternative installation comprising one 40-watt lamp supplied from a 220-volt network; and

Fig. 12 represents an installation of the same type as that of Fig. 11 but comprising an additional igniter electrode.

In the mounting diagram for a lighting installation comprising a 20-watt hot-electrode fluorescent gas discharge lamp 1 shown in Fig. 1, the hot-electrodes 2, 3 of the lamp 1 are connected in. a resonant oscillator circuit which is tuned approximately to the frequency of the 220- volt A. C. supply network. The installation comprises a standard choke coil unit of the type and size used in conventional installations comprising a 40-watt fluorescent gas discharge lamp in combination with a separate starter device. Such choke coil units are known in the trade as 40-watt choke coil units and will therefore be referred to as such; they comprise two choke coils symmetrically wound on a common core and having each a pair of terminals so that they are individually connectable. In the present diagramm, each of the said two choke coils 4, 4' of the unit is connected in the said resonant circuit between one of the two electrodes 2, 3 of the lamp 1 and the corresponding supply line. The resonant circuit further comprises a capacitor 5 of 3.6 microfarads connected in series with the choke coil 4, and a further choke coil 6 formed by one of the two choke coils of another conventional 40-watt choke coil unit, the other choke coil of that unit remaining unconnected. Outside the fluorescent lamp 1 an igniter electrode 8 extending substantially over the whole length of the lamp is arranged, which electrode is connected to the mass of the supporting armature and also, through a current limiting resistor 9 of 2 megohms to the choke coil 4 so that the tension between the igniter electrode 8 and the electrode 2 of the lamp 1 is that existing across the capacitor 5. Alternatively, this igniting electrode could be connected to one of the lamp electrodes through the intermediary of a current-limiting member as shown in German Patent No. 915,249, provided that the somewhat decreased reliability with which the lamp is ignited with this alternative arrangement is suflicient.

When the A. C. supply is switched in, a current passes through the described resonant oscillator circuit, whereby the electrodes 2, 3 are heated up. Further, thefluorescent lamp is ignited on account of the tension maintained between its elecrodes by, the choke coil 6 of the resonant circuit. After the lamp has been ignited, the choke coil 6 of the resonant circuit is practically shortcircuited by the lamp 1 and there is only a small residual current flowing through each of the electrodes 2 and 3 and through the choke coil 6. A capacitor 10 of 40,000 picofarads is provided for preventing radio interference. The power factor is capacitive and amounts to 0.33.

The diagram shown in Fig. 2 is basically similar to that of Fig. 1 but comprises three 20-watt fluorescent lamps 1, 1' and 1" connected in series. The entrance choke-coil unit again is of the above-mentioned conventional or standard 40-watt model and comprises two choke-coils 4, 4'. The capacitor 5 connected in series with the lamps has a capacitance of 3.2 microfarads and the three choke coils 6, 6' and 6" connected in parallel each with one of the lamps 1, 1' and 1" are formed each by one of the two coils of a standard 40-watt choke coil unit, so that two further such units are required, one coil of one of them remaining unconnected. The other parts of the installation are as described in connection with Fig. 1. The power factor is capacitive and amounts to about 0.73.

In the installation diagrammatically shown in Fig. 3 there are four 20-watt fluorescent lamps 1, 1', 1" and 1". Here again, the entrance choke-coil unit is of the standard 40-watt type and comprises two choke coils 4, 4'. The capacitor 5 has a capacitance of 3.5 microfarads and each of the four oscillator choke coils 6, 6', 6" and 6" consists of one half, i. e. one choke coil, of a standard 40-watt unit, so that only three such units are required in all, including the entrance unit. In all other respects, the installation and its mode of operation are similar to that of Fig. 1. The power factor amounts to 0.95 on the capacitive side.

Fig. 4 shows a connection diagram for two 40-watt fluorescent lamps 1 and 1' connected in series. The entrance choke-coil unit, comprising the two choke-coils 4 and 4, is of the standard 40-watt type. The capacitor 5 has a capacitance of 3.5 microfarads and a further 40- .watt standard choke-coil unit 6, 6 is connected in parallel with each of the lamps 1, 1', the two choke coils of each of these units being connected in series with each other. Thus, three standard choke-coil units are required in all. With a supply voltage of 220 volts and a frequency of 50 cycles per second, the power consumed is 99 watts and the power factor is 0.86. An advantage of this particular mounting is that it is not sensitive to voltage variations. With supply voltages varying between 180 volts and 250 volts, the power consumption varies between 82 and 110 watts and the current varies between 0.47 and 0.56 ampere. Depending on the combination, ignition is more or less smooth, i. c. it occurs when the electrodes are insufliciently or well heated respectively, which is important for the useful life of the fluorescent lamps. Because preheating of the electrodes is not ideal with the arrangement according to Fig. 4, a hot-conductor or negative resistor 7, 7' is connected in series with each pair 6, 6 of oscillator choke-coils. These hotconductors each have a resistance of about 500 ohms when cold and of less than 5 ohms when hot and they ensure that ignition of the fluorescent lamps 1, 1' is delayed until the electrodes 2, 3 and 2', 3' have been sutficiently heated.

Fig. 5 shows a mounting diagram for one 40-watt lamp 1, with a network voltage of 125 volts. In addition to an entrance choke-coil unit comprising two choke-coils 4, 4', an oscillator choke-coil unit 6 also comprising two choke-coils is used, these latter choke-coils being connected in series with each other. Both choke-coil units are of the above-mentioned standard 40-watt type and the capacitor 5 has a capacitance of 5 microfarads. The power consumption is 58 watts and the capacitive power factor is about 0.93. In combination with an auto-transformer connected in the supply line, this mounting is suitable for a universally adaptable installation e. g. for supply voltages of 110, 125, 145 and 220 volts. The induction in the core of the auto-transformer may be chosen in such a way that instead of a capacitive power factor, an inductive power factor cos go equal to 0.9 or more results.

The alternative embodiment disclosed in Fig. 6 is similar to that shown in Fig. 5 in that it also comprises a 40-watt fluorescent lamp and is supplied with a 50-cyclesper-second alternative current at a voltage comprised between 110 and 130 volts, but the entrance choke coil group 'here comprises two standard choke coil units, one comprising two choke coils 4 and the other comprising two choke coils 4'. Each pair of corresponding choke coils of the two units is connected in parallel in one of the branches of the supply circuit so that each branch comprises one of the choke coils 4 and one of the choke coils 4 and the arrangement in the two branches is symmetrical. The capacitor 5 in one of the said branches has a capacitance of 7 microfarads. Thus, this installation requires one standard 40-watt choke coil unit more than that shown in Fig. 5, but its efliciency is much better and its operation more economical. With a ll0-volt supply at 50 cycles per second, the power consumption is 49 watts, the input current is 0.51 ampere, and the power factor cos go is about 0.88 (capacitive).

Fig. 7 is a mounting diagram for two 65-watt fluorescent lamps 1 and 1' connected in series, with a 220-volt 50- cycle current supply. The entrance choke-coil group comprises two 40-watt standard units, one comprising two choke coils 4, 4 and the other comprising two choke coils 4, 4' symmetrically connected in the same way as in the installation according to Fig. 6. The oscillator choke-coil group comprises two standard 40-watt chokecoil units 6, 6', each connected in parallel with one of the lamps 1, 1 and the two choke-coils of each unit being connected in series with each other. Accordingly, four standard 40-watt choke-coil units are required in all in this installation. The capacitor 5 which is connected in series in one of the branches of the circuit has capacitance of 5 microfarads. To warrant adequate preheating, a hot conductor 7, 7' is connected in series with each pair 6, 6' of oscillator choke-coils. The power consumption with a 220-volt, SO-cycle supply is 136 watts, the input current is 0.7 ampere and the power factor cos rp is about 0.88.

Fig. 8 discloses a mounting diagram for one lOO-watt fluorescent lamp 1 with a l25-volt, SO-cycle current supply. The entrance choke-coil group here comprises two standard 40-watt choke-coil units each comprising three choke-coils 4, 4 and 4" respectively, the three chokecoils of each unit being connected in parallel each in one branch of the circuit with the corresponding chokecoils of the other units in a symmetrical arrangement. The oscillator choke-coil group comprises two standard 40-watt choke-coil units 6, 6' each having its two chokecoils connected in series with each other and the two units being connected in parallel with each other and with the lamp 1. T he capacitor 5 provided in one of the branches of the circuit has a capacitance of 14 microfarads. In the oscillator circuit, a hot-conductor 7 is provided to improve the preheating of the electrodes 2, 3 of the lamp 1. The power consumption witha volt supply is 120 watts, the input current. is 1.15 amperes and the power factor cos (p is about 0.83 (capacitive). With a transformer for, .e. g. 125, /220 volts connected in the supply, the mounting can be made universally adaptable to all usual network voltages and the power factor cos (,0 will become about 1.0

Fig. 9 represents the connection diagram for two 100- watt fluorescent lamps 1 and 1' connected in series and for a supply voltage of 220 volts at 50 cycles per second. The entrance choke coil group comprises two standard 40-watt choke-coil units each comprising three choke coils 4, 4', 4" the individual choke coils of which are symmetrically connected in the same way as in the installation according to Fig. 8. Each of the two groups of oscillator choke coils comprises two standard 40-watt units 6, 6' and 6", 6", respectively, the two choke coils of each of which are connected in series with each other, the two units being connected in parallel with each other as in the installation according to Fig. 8. In all, the installation comprises four standard 40-watt choke-coil units. The series capacitor 5 in one branch of the circuit has a capacitance of 11 microfarads. In the oscillator circuit a hot-conductor 7, 7 is provided for each lamp 1-, 1'. The power consumption with a 220-volt supply is 225 watts, the input current is 1.26 amperes, and the power factor cos (p is about 0.82 (capacitive). Althougha comparatively large number of standard 40-watt choke-coil units is required in this arrangement, this installation is much more economical than the 100-watt-lamp installation hitherto used which could be manufactured in small numbers only and in which comparatively expensive starter devices and starter casings and a barrier choke coil for the compensating capacitor were required.

As may be seen from the foregoing examples, a great variety of mountings can be provided for practically all commercially available hot-electrode fluorescent lamps. Similar mountings as those shown in Figs. 1 to 3 for 20- watt fluorescent lamps can also be established, for instance, for l3-watt, l4-watt, or l5-watt lamps and also for 22-watt, 32-watt and 40-watt lamps of circular shape, where only the series-connected capacitor in the supply connection should have somewhat different capacitance values. All these installations can operate without a starter switching service and they comply with all requirements of room lighting, such as compensation, choking, sharp igniting with sufficient preheating, long life of the lamps, correct radio interference prevention, good lighting efficiency, etc. It has been found that although some of these installations do not work in a quite satisfactory way at temperatures of less than 10 to 15 C. with ordinary fluorescent lamps, they can be made to work perfectly at temperatures down to about C. by using so-called cold-resistant lamps.

Fig. 10 shows a further mounting for one 40-watt, 0.42- ampere lamp with a 220-volt, 50-cycle current supply. In this mounting, two standard 40-watt choke-coil units 6 and 11, each having its two choke coils connected in series, are connected in series with each other as well. This arrangement permits to attain an igniting voltage of more than 400 volts and thus safely ensures ignition without the provision of an igniter electrode. The entrance choke-coil group comprises one standard 40-watt choke-coil unit incorporating two similar choke coils 4, 4. The series-connected capacitor has a capacitance of 3.6.microfarads. The power factor of this installation is about 0.5 (capacitive). The said capacitor 5 can be incorporated in the choke-coil unit to provide a standard choke-coil capacitor unit. Such units comprising two choke coils and a capacitor are already being manufactured in large numbers for use in over-compensating adapter units for fluorescent lamp installations of the conventional type comprising starter units for glow discharge starting. The same choke-coil capacitor units being usable both with the mounting shown in Fig. 10 and in such conventional over-compensating adapters, it is possible to manufacture them in large numbers for both purposes. To ensure good preheating of the electrodes 2 and 3 of the lamp 1, a hot conductor 7 having about 1000 ohms resistance when cold is connected in the igniting circuit.

The alternative mounting shown in Fig. 11 also serves for supplying one 40-watt fluorescent lamp from a 220- volt, Sit-cycle network but it operates with an inductive power factor of about 0.5. The capacitor 5 in this case is connected in parallel with the lamp and in series with the two choke coils 6 of the standard 40-watt choke-coil units so as to form with the latter a standard choke-coil capacitor unit of the type referred to in connection with Fig. 10. The two choke coils which this unit comprises are connected in series with each other. The capacitor 5 preferably has a capacitance of about 3 to 3.5 microfarads. The entrance choke coils 4, 4' a're'again those of a standard 40-Watt choke-coil unit and in the capacitor 10 provided for preventing radio interference a capacitance of about 50,000 picofarads is sufiicient. As in the mounting shown in Fig. 10, an igniting voltage of more than 400 volts and thus a most reliable ignition is obtained without the use of an igniter electrode. To improve preheating, a hot-conductor 7 having a resistance of about 1000 ohms when cold is provided in the igniter circuit. The two mountings according to Figs. 10 and 11 can be combined into a so-callcd dual mounting for operating two lamps with a combined power factor of approximately 1. With lamps individually connected, the combination can be chosen in such a way that the prescribed power factor is attained in the whole lighting installation.

Fig. 12 represents a mounting similar to that shown in Fig. 11 but an additional igniter electrode 8 is pro vided. This electrode 8 is connected to the capacitor 5, through a current-limiting safeguard resistor 9, in such a way that the voltage existing across the capacitor 5 is etfective between one of the electrodes 3 of the lamp and the igniter electrode 8, which latter may consist of the armature supporting the lamp. The provision of the hot-conductor 7 is immaterial in this arrangement; also, this hot-conductor could be placed at any other point of the igniting circuit parallel to the lamp. This mounting comprising an igniter electrode should prove particularly suitable in installations in which the ambient temperatures are very low and also in lighting installations which can be regulated by means of variable transformers such as those used in theatres etc. Of course, the mounting represented in Fig. 10 can be complemented in the same way with an igniter electrode.

W-hatl claim is:

1. in a lighting installation, a pair of A. C. supply terminals, at least two fluorescent gas discharge lamps each having a pair of opposite hot-electrodes, one hotelectrode of one lamp and one hot-electrode of the other lamp being mutually interconnected in series with each other, at least one choke-coil unit of standard construction and size comprising a core and two separately connectible choke coils symmetrically wound on said core, each of said coils being connected in parallel with one of said lamps between the two hot-electrodes thereof in series with the hot-electrodes, the said interconnected hot-electrodes of the two lamps being connected in series between the one end of one of the said choke coils and the other end of the other of the said choke coils to provide equi-directional flow of current around said core through both said choke coils, at least one further chokeco-il unit of the same standard construction and size as the aforesaid choke-coil unit, the two choke coils of said further choke-coil unit being symmetrically connected each between the non-interconnected hot-electrode of one of the said lamps and a separate one of said terminals, and a capacitor connected in series with said lastmentioned choke coils and hot-electrodes to provide an oscillator circuit therewith.

2. In a lighting installation as set forth in claim 1, an igniter electrode arranged outside said lamp and extending substantially over the whole length thereof, and a current limiting member connected between said igniter electrode and a point of the circuit.

3. In a lighting installation as set forth in claim 1, an igniter electrode arranged outside said lamp and extending substantially over the whole length thereof, and a resistor connected between said igniter electrode and a point of the circuit.

4. In a lighting installation, a pair of A. C. supply terminals, at least one fluorescent gas discharge lamp having a pair of opposite hot electrodes, an inductor connected between said hot electrodes in parallel with the lamp, a choke coil unit of standard construction and size comprising a core and two separately connectible choke coils symmetrically wound on said core, each of the two choke coils being connected in series between one of the electrodes of said lamp and one of the terminals}; 3 5

a capacitor connected in series between one of the said choke coils and the inductor, an igniter electrode outside 7 the lamp, and a resistor connected between said igniter electrode and the connection between said choke coiland said hot electrode.

(References on following page) V V 7 References Cited in the file of this patent 2,170,443

' 2,334,568 UNITED STATES PATENTS 2,429,415 2,056,647 De Bruin Oct. 6, 1936 2,438,556 2,170,447

Edwards Aug. 22, 1939 5 2,504,549

8 Edwards Aug. 22, 1939 Lord Nov. 16, 1943 Lemmers Oct. 21, 1947 Hehenkamp Mar. 30, 1948 Lemmers Apr. 18, 1950v 

